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<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

</body>
<script>
  function fn1() {
    console.log(arguments)
    console.log(this)
  }
  fn1(1, 2, 3)

  var obj = {
    name: '李四',
    age: 20,
    sayHi: function () {
      console.log(this)
      console.log('我是' + this.name + '，今年' + this.age + '岁')
    }
  }

  obj.sayHi()

  var animals = ['🐟', '🐟', '🐠', '🐠', '🐡', '🐡', '🦐', '🦐']
  var catArr = animals.map(item => '😺')
  console.log(catArr)

  var numbers = [3, 6, 1, 10, 29, -1, -100]
  var newNumbers = numbers.map(item => item * 2)
  console.log(newNumbers)

  console.log(numbers.find(item => item < -10))
  console.log(numbers.findIndex(item => item < -10))

  console.log(numbers.reduce((preValue, curValue) => preValue + curValue))

  console.log(numbers.reduce((preValue, curValue) => preValue * curValue))

</script>

</html>